The present invention relates to an electric induction motor stator encapsulated in an insulating envelope or housing closed at the magnetic circuit yoke and at the winding turns right up to the end portion of the laminations at the entrance to the air gap and open over the whole of the cross-section of the air gap in order to receive the rotor which is housed in a rotor tube. It also relates to induction motors that are fitted with such a stator.
Induction motors are by far the electric motors that are the simplest to construct and have the best yield when they run continuously under normal speed conditions, in other words not too far from their speed of synchronism with the frequency of their electrical supply network. The magnetic circuit of the stator is generally made up by a stack of laminations cut out from the same initial lamination material in order to constitute a complete motor the rotor of which is in principle able to withstand any overheating condition since its squirrel-cage electrical circuit is currently formed from copper or aluminum bars that are directly in contact with the noninsulated laminations of the rotor. The stator circuit which has to withstand the electrical supply voltage on several mutually insulated windings is, on the other hand, much more fragile and needs a lot more space because it surrounds the rotor in the majority of applications and the problem of replacing it occurs much more frequency than is the case for the rotor which is subject rather to problems involving its bearings.
The present invention sets out to provide a stator for an induction motor which can be readily replaced independently of its rotor, the latter generally being linked to a driven rotating component which, in equipment such as pumps, can be completely isolated from the stator by an environment-tight wall. The stator in accordance with the invention requires, because of its dismountable nature, to be light, easy and inexpensive to manufacture while at the same time having exceptional qualities as regards its compactness, electrical insulation and environmental sealing properties.